The present invention relates to a power generator containing fuel cell(s), more particularly to such a power generator with improved responsiveness to rapid rise of load.
Power generators using fuel cells (hereinafter referred to as "fuel-cell power generators") are known as for instance disclosed in Japanese Patent Publication No. 56231/83 and Japanese Patent Laid-Open No. 163183/83. In the conventional power generators of this type, when there occurs a sharp change of power load connected to the fuel cell, for instance, a change from 25% load to 100% load, it is required to quickly increase the gas feed to the hydrogen electrode of the cell to cope with such change of load. For effecting such a quick increase of gas feed, it is necessary to rapidly enlarge the openings of valves such as main fuel feed regulating valve, air regulating valve and vapor regulating valve.
Generally, however, the valve control systems are subject to a certain time lag in their operation even if the valves involved are relatively small in size, and usually they suffer a delay of action for a time of from about 2 to about 10 seconds. The conventional fuel-cell power generators were unable to keep pace with the change of load during the period of such delay of action to incur a shortage of output power during this period. This is a serious problem especially with the on-site type fuel-cell power generators which are set and used independently of the general power supply because the change of load occurs very quickly and frequently in such on-site type power generators.